The park tickets are priced at $21 and $14.  The number of $21-dollar tickets available is  1¹₂ that of the number of $14-dollar tickets. 3 out of 4 of the $21-dollar tickets and all the $14-dollar tickets were sold. The ticket sales amounted to $3311. How much more would have been collected if all the tickets were sold?

	$21	$14
Comparing $21 and $14 tickets at first	3x4 = 12 u	2x4 = 8 u
Before	4x3 = 12 u
Change	- 3x3 = - 9 u	- 8 u
After	1x3 = 3 u	0 u

The number of 21 tickets at first is repeated.  Make the number of 21 tickets the same.  LCM of 4 and 3 is 12.

1¹₂ = ³₂

Number of $21 tickets : $14 tickets = 3 : 2

	$21	$14	Total
Number	9 u	8 u
Value	$21	$14
Total value	189 u	112 u	$3311

Total amount collected from the sale of the sold tickets
= 189 u + 112 u
= 301 u

1 u = 3311 ÷ 301 = 11

Number of $21-tickets left unsold
= 3 u 
= 3 x 11
= 33

More amount to be collected if all the tickets were sold
= 33 x 21
= $693

Answer(s): $693